Induction voltage and torque transfer devices



2,872,603 INDUCTION VOLTAGE AND TORQUE TRANSFER DEVICES Filed June 13, 1955 D. L. HERR Feb. 3, 1959 5 Sheets-Sheet 1 WWW y INVENTOR. DONALD L. HERR e w'om aw A 7' TURN E YS Feb. 3, 1959 I D. L. HERR 2,872,603

INDUCTION VOLTAGE AND TORQUE TRANSFER DEVICES Filed'June 13, 1955 5 Sheets-Sheet 2 INVENTOR. DONALD L. HERR BY 5114M? & 724W ATTORNEYS D. L. HERR 2,872,603

5 Sheets-Sheet 5 1 M 1 K v a w FIG.

INVENTOR.

DONALD L. HERR BY We Armle/vEys Fla? Feb. 3, 1959 INDUCTION VOLTAGE AND TORQUE TRANSFER DEVICES Filed June 13, 1955 United States Patent INDUCTION VOLTAGE AND TORQUE TRANSFER DEVICES Donald L. Herr, Santa Monica, Calif.

Application June 13, 1955, Serial No. 514,924

Claims. (Cl. 310-111) The invention relates generally to electromagnetic transfer devices and more particularly, to a novel construc tion and dimensioning of the basic components of such devices for realizing optimum electromagnetic and mechanical configurations in their manufacture. v

Electromagnetic voltage and torque transfer devices are well known in the art and find wide application in analog computers and fire control systems. Basically, these devices comprise a rotor body secured to a control shaft and concentrically positioned for rotation within a surrounding stator body. Both the rotor and stator are provided with discretely distributed, mechanically matched conductor windings. By this arrangement, the degree of inductive coupling between the rotor and stator windings when one or the other is electrically excited, is dependent upon the angular relationship of the rotor with respect to the stator. For example, in the case of an electromagnetic resolver, the rotor and stator are each provided with two windings mechanically 90 degrees apart. An alternating input signal applied to one of the stator windings will then result in an output voltage from one of the rotor windings proportional to the product of the initial input signal and the sine or cosine of the angle of the rotor shaft or windings with respect to the stator. There is thus provided a device which may be used to continuously compute the sine or cosine of a varying angle.

It will be immediately evident, that the practical value of any type of voltage or torque transfer device, will depend upon the accuracy with which the device can generate the desired function. The degree of accuracy which may be achieved in this respect, is in turn dependent principally upon two factors: first, on how close it is possible to approach a mathematically idealized optimum electromagnetic flux path configuration in the rotor and stator as limited by the use of given magnetic materials, windings of finite dimensions, physical airgaps, and discontinuities in the magnetic bodies resulting from slots for accommodating the conductor windings; and second, on how close it is possible to approach an optimum mechanical configuration of the conductor windings, as. limited by the skill and accuracy with which these windings can be wound, applied, and positioned on the rotor and stator bodies.

With regard to the first factor, an optimum electromagnetic configuration is attained when the components are dimensioned to insure a maximum linear flux density at a maximum saturation level, with minimum magnetic noise, null voltage, and variations of leakage flux with different rotational positions of the rotor. Further, an optimum electromagnetic configuration results when there is a minimum of time harmonic and time quadrature generation.

With regard to the second factor which is of equal importance, an optimum mechanical configuration is attained when the conductor windings are applied and positioned in the rotor and stator slots in an accurate and consistent manner, with uniform tension and uniform 2,872,603 Patented Feb. 3, 1959 slot loading in accordance with the characteristics of the function which it is desired to generate. Further, the windings must be applied and positioned in a manner to insure uniform magnetostriction of the magnetic bodies as a result of the windings. Matched windings and windings to be made proportional to one another must be uniformly applied, tensioned, and positioned to insure accuracy in the generated function. Interleaved multiple windings must be properly positioned in the slots to insure equalization of the electrostatic and electromagnetic coefficients. 1

Heretofore, conventional stator windings have been laterally formed and hand inserted into the stator slots. This procedure is presently necessary because of the stator construction and the apparent necessity of lateral windings in order to provide the desired flux paths.

Such hand insertion of lateral windings has many disadvantages. Aside from the fact that the manual insertion operation is tedious, time consuming, and subject to human error, it does not insure a uniform tension in the conductors nor utilize the slot areas to greatest advantage. Further, end turns must be manually formed resulting in an overhang and waste of copper in the final device. Oftentimes, compression of the end turns into a small space can result in abrasion of the conductor insulation and possible short circuits between the conductors themselves or between the conductors and ground. Compression and twisting of the conductors may also result in open circuiting of the windings.

Bearing the above factors in mind, a primary object of the present invention is to provide an electromagnetic transfer device so designed and dimensioned as to result substantially in an optimum electromagnetic and mechanical winding configuration, whereby such device approaches a mathematically idealized system.

More particularly, an object is to provide a device of the above nature, in which the dimensioning of all of the components for realizing an optimum electromagnetic configuration may be derived from one basic given dimension and a knowledge of the desired number of slots in the rotor and stator. This given dimension is preferably the radius of the stator body whereby it is usually dictated by the physical dimensions of a given space in which the device is to be fitted. All the other component dimensions may then be scaled down or up in accordance with the given stator radius.

Another important object of the invention is to provide a novel stator design that meets the above objects, but which will enable the stator to be machine wound thereby eliminating the disadvantage of coil pre-winding, manual insertion and endturn forming, and insuring uniiormity and precision in the stator windings themselves in order to provide an optimum mechanical configuration.

In this respect, a further object is to provide a stator which may be machine wound but which will provide magnetic flux paths corresponding to the flux paths established in conventional laterally wound stators with the added advantages of both optimum electromagnetic and mechanical configurations.

These and many other important objects and advantages of the present invention are attained by first selecting the desired number of rotor and stator slots and then mathematically deriving from one basic parameter, all of the dimensions of the stator and rotor components such that an optimum electromagnetic configuration results and the operation of the transfer device approaches I as close as possible the theoretical operation of an idealparameter is with the slots for supporting toroidal stator windings. Thus, rather than laterally winding the stator, the windings are toroidal and a conventional toroid winding machine with only inconsequential modifications may be employed to wind the stator. The design of the external teeth, slot dimensions, and other components, are mathe" matically determined in accordance with the above mentioned basic'parameter .so that the magnetic flux paths established by the toroidal windings correspondto those presently attained by the use of lateral windings, with the added advantage of a substantially optimum electromagnetic and mechanical configuration.

A greater appreciation of the significance of this invention will be had by referring to the following detailed description and accompanying. drawings, in which:

Figure l is a partly cut-a-way schematic perspective view of the basic components of an electromagnetic transfer device designed in accordance with the present invention;

Figure 2 is a plan View of one of the stator body lamii the rotor body'laminations;

. Figure 4 illustrates a set of equations for deriving the dimensions of the stator body shown in Figure 2, in order to provide an optimum electromagnetic configuration;

Figure 5 illustrates a second set of equations for deriving the dimensions of the rotor body of Figure 3;

Figure6 is a schematic perspective view of a portion of a conventional type stator body with lateral. windings and flux path directions; and

, Figure 7 is a schematic view, similar to Figure6 but showing a portion of a stator body designed in accordance with the present invention with toroidal windings and flux path directions.

*Referring to Figure 1, there is shownan electromagnetic transfer device comprising a cylindrical housing 10 made of magnetic shielding material and arranged to support withinits interior a stator body 11. Coaxially positioned within the stator ii is a rotor body 12 secured to a rotor shaft 13. e

The shaft 13 is rotatably supported by bearing plates 14 and 15' on the housing 16. Each plate is provided with bearings 1n and 17, respectively, for the shaft 13.

Theend of the shaft 13 projecting beyond the bearing plate 14, is provided with slip rings 18, 19, 20, and 21, each internally connected respectively to conductor leads 22, 23, 24, and 25. These conductors pass within the shaft 13 to connect to the rotor windings, which are, not shown in Figure l for purposes of clarity. Suitable conductors.

26, 27, 28, and 29 serve to pass signals from these slip --The stator winding ends 31, 32, 33 and 34 may be brought directly outthrough the bearing plate 14 to suitable exterior terminals on thel'terminal plate 30. The stator windings are not shown in Figure 1 to avoid obscuring the drawing;

In operation, and with suitable windings on the stator and rotor (not shown), an alternating signal is applied to one or both of the stator winding terminals and an output si nal taken from one or bothof the rotor Winding terminals, or vice-versa. The magnitude of the output signal at any given instant of time will depend upon the angle of the rotor shaft 13 with respect to the stator.

Both the stator 11 and rotor 12 are made up of laminated magnetic material of high permeability. By making the laminations of a thickness preferably less than 0.014 of an inch, a large ratio of stored magnetic energy the magnetic structure is obtained and is sufiicient to perfollows ent invention, this lamination is dimensioned toprovide a stator construction which will, first, provide an optimum electromagnetic configuration, and second, permit the stator windings to be machine Wound to provide an optimum mechanical winding configuration.

As shown, the stator lamination comprises an annular plate member 35 having a plurality of radially inwardly projecting bars 36 defining'stator slots 37. About the periphery of the plate member 35, there are provided'a' plurality of radially outwardly projecting teeth 38, each toothbeing in radial alinement with. one of the bars 36 as shown. 7 These teeth constitute part of the magnetic structure of the stator and serve as guiding walls in cooperation with the. slots to accommodate toroidal windings, as will become clearer as the description proceeds. in Figure 3 there is shown one of the laminations of the rotor 12. This lamination comprises an annular plate 39 having a central opening 40 adapted to receive and be secured to the rotor shaft 13 of Figure 1. As shown, plate 39 has a plurality of radially projecting bars 41 defining rotor slots 42 in which the rotor windings are placed.

The number of'slots in the stator and rotor will depend upon the desired purpose of the transfer device. In the case of an electromagnetic resolver, for example, it is imperative to obtain identical distribution of the two stator windings and identical distribution of the two rotor-windings in the slots 37 and 42 of the stator and rotor respectively,.with the axes of electrical symmetry of said; two

windings in each; mechanically 90 degrees apart. In

order to achieve this distribution, the number of slots in the'statorill and rotor 12 are made integral multiples'of four; In addition; the number of slotsin the stator 11 is 'preferably'four or more greater than the number of slots in the rotor 12 with aminimum number of twelveslots in the stator 11 and a minimum number of eight slots in the rotor 12. In Figures 2 and-3, the stator is shown withtwenty slots and the rotor with twelve slots. It is to in the corresponding Figures 2 and 3 and are defined'as General p=Number of stator slots. q =Number 'of rotor slots. r e Outside .radius of stator to tip of tooth elements: rThisv alue may be arbitrarily selected in accordance with the desired'outside physical dimensions of the transfer device.

' Stator A Area of each stator slot. 7 r =Radius of'stator to base of. external teeth. w =Width between parallel sides of stator bar. r =Radius to rear of stator slot.

r Radius to front of stator Slot. r =Radius of curvature of rear portion of stator slot. rf Radius of curvature of, front portion of stator slot. c =Distance between centers of two curvatures.

t=Depth and width of stator slot entrance.

mit the transfer device to function with a high degree of laminations of the stator 11; In accordance with the prese Air gap between'stator and rotor.

Rotor A,. .=Area ofrotor slot. 7

r ,.=Radius of central opening in rotor;-

w,-=Width between parallel sides of rotor ban. r,,.=Radius to bottomof rotor slot.

rg=Radiusto top of rotor slot. r =Radius of curvature of top portion ofrotor slot.

x =.Radius of curvature: of bottom portion of rotor slot.

c-,==.Dista'nce between; centers of two :curvatures'.

I=Depth and width of rotor slot entrance (same as stator).

The slots for both the stator and rotor are tear-drop in shape and are defined by two circles of different radii, having spaced centers, peripheral portions of the circles being joined by straight tangent lines. The equations set forth in Figures 4 and 5 ultimately determine each of the above dimensions in terms of r p, and q. After the values for p and q have been selected, the quantities will depend solely upon the selected external radius of the stator r Insofar as the optimum electromagnetic configuration is concerned, the axial stack length of the rotor and stator are of secondary consequence. This length is determined in accordance with the impedance of the particular electrical system to which the transfer device is applied, and the physical limitations imposed by its location.

As an example of actual values of the various dimensions defined above, there follows a table giving the dimensions for three basic case sizes of electromagnetic transfer devices having toroidally wound stators and providing optimum electromagnetic and mechanical configurations in accordance with the invention. In the following table the stator and rotor slots p and q are set equal to and 12 respectively:

Case Size 11" "15 (Inches) (Inches) Case, 0. D 1.06200 1.43700 Wall thickness"...

Referring now to Figures 6 and 7, there is schematically illustrated in Figure 6 the magnetic flux paths established in a conventional stator having lateral windings, and in Figure 7 the magnetic flux paths established by the toroidal windings of the present invention, again using the example of the resolver.

In Figure 6 there is shown a stator 43 having a series of slots 44, for receiving laterally wound conductor winding groups 45, 46, 47, and 48. Only-a few conductors are shown in each winding group tosimplify the drawing. The winding groups are conventionally formed on rectangular type frames and then inserted into the proper pairs of slots by manually urging the conductors through the slot openings 49 adjacent the airgap. Thus, the group of conductors is formed on a relatively small rectangular frame and urged into a first pair of adjacent slots 44, passing up one slot and passing down the adjacent slot. After several such turns, to form the first group, the conductor is crossed over to the next 'adja- 6 again crossing over as by conductor 52 to another pair of slots to form the winding group 48, and so forth.

In the case of prior art lateral windings as schematically depicted in Figure 6, current passing through the conductor groups as indicated by the small arrow heads on the individual conductors, will establish a flux path through the airgap in a radial direction, as indicated by the large arrow 53.

The winding conductors are shown in Figure 6 as extending straight across the face of the stator from one slot to the other to form stator end turns. When the rotor is assembled within the stator, portions of these winding end turns passing across the stator face must be pushed radially away from the central area of the face to permit the rotor shaft to extend through the stator. The winding end turns thus tend to bunch up on the end faces of the stator and the tension and positioning of the windings within any one or more slots is subject to shifting. During final assembly of the device, within an outer casing, these end turns are compressed as much as possible. Such compression may not only cause short circuit, but also loosen some of the conductors in the slots resulting in further changes in the winding tension.

Further, with the use of lateral windings there is no assurance that the conductors are distributed in the slots in a mechanically uniform and consistent manner as to insure precise equalization of the electrostatic and electromagnetic coefiicients. The matching of windings and consistent proportionality of multiple windings is also subject to error.

Referring now to Figure 7 there is shown a portion of a stator 54 designed in accordance with the present invention, comprising a plurality of slots 55, and projecting teeth 56. Passing down through each slot and up between corresponding tooth elements are two Sets of conductor group windings S7 and 53. The set 57 comprises toroidal winding groups 59, 60, 61, 62, and 63 and the set 53 comprises toroidal Winding groups 64, 65, 66, 67, and 68.

The top lamination 69 of the stator 54 is made of insulative material and provided with narrow grooves such as the groove 70 within which a cross-over conductor 71 between adjacent windings, lies.

In the simplified embodiment shown in Figure 7, the group windings in set 57 are connected together and the group windings in set 58 are connected together by suitable cross-over conductors. The Winding set 57, however, is a separate winding from the winding set 58. With current flowing through the conductors of each set as indicated by the arrow heads, flux paths 72 and 73 will be established in the stator body and pass radially across the air gap into the rotor body as indicated by the arrow 74. The paths 72 and 73 then close on themselves. In Figures 6 and 7, only the extreme flux paths are illustrated.

It will be seen, accordingly, that the toroidal windings produce an identical radial flux path direction as the prior art lateral windings. This flux however is in the stator body and carried thereby, rather than being generated in the air gap. Further, because of the toroidal type windings it is possible to use a conventional toroidal winding machine with only inconsequential modifications.

Toroidally winding the stator by machine, as opposed to the old method of hand inserting lateral windings provides an optimum mechanical Winding configuration. Thus, machine winding insures that the conductor windings will be applied and positioned in an arcuate and consistent manner with uniform tension and slot loading. Machine winding further permits the windings to be applied and positioned in a manner to insure uniform magnetostriction of the stator body as a result of the windings. Matched windings and windings to be made proportional to one another may be uniformly applied,

tensioned, and positioned to insure accuracy in thejg'enerated function." Further, interleaved multiple windings may be properly positioned in the slots to insure equalization of the "electro-static and electromagnetic coefficients.

' The stator design and use of toroidal windings eliminates the formation of large end turn bunching Crossover conductors need extend no more than the distance between adjacent slots. Once the windings have been applied, there is no need to reposition them nor will any shifting occurwhen the stator and rotor are assembled in acasing.

Further the toroidal configuration permits the use of larger diameter conductors resulting in a decreased resistance in the windings and a higher Q. 7 V

'From'the: above description, it will be seen that the present invention provides an electromagnetic "transfer clevice'having both an optimum electromagnetic configuration and an optimum mechanical Winding configuration.

What is claimedis:

1. An electromagnetic induction transfer device comprising: a cylindrically shaped stator body having a central opening; a cyiindrically shaped rotor body coaxially positioned within said, central opening; said stator body including radially inwardly directed stator barsdefining tear drop shaped'stator slots between adjacent bars, the peripheral ends of said tear drop shapes being defined by arcuate portions of two circles of difierent radii having centers spaced radially with respect to the central axis of said stator body, the arcuate portion of the smaller of said circles ,bcingbroken to define a stator slot entrance, and the sides of said tear drop shapes being defined by tangentlines forming the sides of adjacent stator bars; said rotor including radially outwardly directed rotor bars defining tear drop shaped rotor slots having rotor slot'entrances and defined by portions of two circles of dififerent radii and spacedcenters'and'tangent lines forming the sides of adjacent rotor bars; said stator and rotor slots being adapted to receive conductor windings; and a plurality of outwardly directed tooth elements forming a part of said stator body in radial alinement respectively with said stator bars, said stator and rotor bodies being physically dimensioned in accordance with.

the following equations:

' a oeoseo as-asst 2872;668 7 g V w p=Number of stator slots; q=Numberof rotor slots; 7

r r =Outside radius of stator'to tip of tooth elements;

A 5=Area of each stator slot;

r -Radius of stator to base of external teeth; w ==Width between parallel sides of'stator bar; r =Radius torear of stator slot; V a

rr5=Radius to front of stator slot;

r =Radius of curvature of. rear portion of Stator slot; r g=Rad1usof curvature of front portion of stator slot; c,='Dist,ance between centers of two curvatures; a

' t=Depth andwidth of stator slot entrance;

A -Area of rotor slot; r =Radiusofcentral opening in rotor; w,=Width between parallel sides of rotor bar; r

r =Radius to bottom of rotor slot;

whereby an optimum electromagnetic flux path configuration is provided.

2.,An electromagnetic transfer device accordingvto claim 1, in-which said stator body tooth elements provide .r guides tor toroidal windings on said stator, the cross sec tional area between said guides being substantially equal to the cross sectionalv area of said slots whereby said stator may beernachine wound to provide an, optimum mechanical winding configuration.

3. In an electromagnetic transfer device, a first member made from magnetically receptive material and provided with slots at spaced positions along one periphery of the member, a second member made from magnetically receptive material and provided with slots at spaced positions along a periphery contiguous to the slots in the first member and disposed relative to the first member to I provide an air gap between the first and second members and disposed for movement relative to the first member, and a plurality of toroidal windings each extending through only one of the slotsin the first member and through a difierentvone of the slots with respect to the slots receiving the other windings and each having a plurality of turns directly controlling the increment in the intensity of the flux extending across the air gap at particular positions for the generation, upon progressive displacements between the first and second members, of an output signal having an incremental pattern directly related to the numbers of turns in the successive windings, the number of turns of the windings in'adjacent slots being different in accordance with the incremental pattern of the flux to be produced at successive positions across the air gap for the generation of a particular arbitrary function.

4. In an electromagnetic transfer device, a first member made from magnetic material and disposed in a loop with a central opening and provided with a plurality of slots at spaced intervals along one periphery of the loop and provided with a continuous portion at its other periphery for the flow of magnetic flux, a second member made from magnetic material and disposed in a loop with a central opening and provided with external dimensions for disposition in telescoped relationship to the first member and for the provision of an air gap between the first and second members and for rotary movement relative to the first member and provided with a plurality of slots at spaced intervals along the periphery contiguous to the first member, and a plurality of windings supported on the first member and looped from the other periphery of the member to the slots at one end and from the slots to the other periphery of the member at the other end and disposed to provide ampere-turns for the flow of unsaturated magnetic flux in the looped direction through the continuous portion of the first member in a pattern of incremental intensity at any position related to the conductor density provided by the windings in the contiguous slots and for the production across the air gap of magnetic flux having patterns of intensity corresponding to the patterns of intensity of the flux in the continuous portion at displaced angular positions to obtain the production of output signals in accordance with the relative rotary disposition of the first and second members and in accordance with the conductor densities of the windings in the successive slots, adjacent windings in the plurality having different numbers of turns in accordance with the increments in flux to be produced at successive positions across the air gap for the generation of a desired arbitrary function.

5. In an electromagnetic transfer device, a first hollow annular member made from magnetically receptive material and provided with slots at spaced positions along one. annular periphery of the member, a second hollow annular member made from magnetically receptive material and provided with slots at spaced positions along the annular periphery contiguous to the slots in the first member and disposed in concentric relationship to the first member to the first member and provided with a number of turns proportional to the value of a ditlerent increment in an arbitrary function defined by two interrelated quantities in which the spacings between successive pairs of slots represents successive increments in a first one of the quantities and in which the number of turns in each slot represents increments in the value of a second one of the quantities for each increment in the first quantity, the windings in adjacent slots having different numbers of turns for the production of successive increments in the second quantity upon the occurrence of successive increments in the first quantity so as to generate the particular arbitrary function and the number and polarity of the turns in the difierent slots being chosen to produce a total flux of zero in the first and second members.

6. In an electromagnetic transfer device, a first member made from magnetically receptive material and provided with slots at spaced positions along one periphery of the member and with bars between the slots and with a continuous portion at an opposite annular periphery of the member, a second member made from magnetically receptive material and provided with slots at spaced positions along the annular periphery contiguous to the slots in the first member with bars between the slots and with a continuous portion at the other periphery of the first member and disposed relative to the first member to provide an air gap between the first and second members and movable relative to the first member in a direction along the first member, and a plurality of windings supported on the first member and looped from the other periphery of the member to the slots at one end and from the slots to the other periphery of the member at the other end and forming a continuous circuit with one another and disposed to provide ampere-turns for the flow of unsaturated magnetic flux through the continuous portion of the first member in a pattern of intensity at any position related to the conductor density provided by the windings in the contiguous slots and for the production across the air gap of magnetic flux having patterns of intensity corresponding to the patterns of intensity of the flux in the continuous portion at displaced positions to obtain the production of an output signal in accordance with the relative movements of the second member along the first member and in accordance with the conductor densities of the windings in the successive slots, each of the windings being disposed in a different one of the slots and being provided with a conductor density directly proportional to increments in the value of a first quantity for successive increments of a second quantity corresponding to the spacings between successive pairs of slots wherein the first and second quantities represent an arbitrary function' to be generated upon successive displacements between the first member and the second member, the windings in adjacent slots having different numbers of turns in accordance with successive increments to be obtained in the first quantity for successive increments in the second quantity as defined by the spacing between the adjacent slots so that the desired arbitrary function can be generated upon successive displacements between the first and second members.

7. In an electromagnetic transfer device, a first hollow annular member made from magnetically receptive material and provided with slots at spaced positions along one annular periphery of the member and with bars between the slots and with a continuous annular portion at the other annular periphery of the member, a second hollow annular member made from magnetically receptive material and provided with slots at spaced positions along the annular periphery of the member contiguous to the annular periphery in the first member and with bars between the slots and with a continuous annular portion at the other annular periphery of the second member and disposed in concentric relationship to the first member to provide an annular air gap between the first and second members and disposed for rotary movement relative to the first member, and a plurality of windings each extending through a dilferent one of the slots in the first member in a direction to produce a flux which extends annularly along the outer periphery of the member and which has at each annular peripheral position an increment in 'asraees intensity related to the conductor density of the windings in the contiguous slots and which extends across the air "ga in a radial direction at a second position removed from the first position and which has at successive positions across the air gap patterns of intensity corresponding to the patterns of fluxes in'the annular direction for the production of output signals having amplitudes indicative at progressive positions of the relative displacement between the first and second members and in accordance with the patterns of the fluxes produced across the air gap upon the progressive displacements between the first and second members, the number of turns in the windings in adjacent slots being difiFerent in accordance with increments in flux to be generated across the air gap at successive positions corresponding to the spacing between the adjacent slots. 7

8. An electromagnetic transfer device as set forth in claim 7 in which each of the windings in the plurality extends toroidally through only one of the slots to'obtain a magnetic coupling to the first member and in which successive windings have a number of turns different from the number of turns in adjacent windings'in accordance with the incremental pattern of flux intensity to be produced across the air gap upon progressive displacements between the first member and the second member.

9. An electroma netic transfer device as set forth in claim 3 in which the first and second members are hollow and annular and are disposed in concentric relationship 7 to each other to provide a concentric relationship between them and in which the second member is disposed for rotary movement relative to the first member.

ll). in an electromagnetic transfer device, a first member made from magnetic material and provided with a hollow annular configuration and with a plurality of slots lar configuration having an outer dimension for rotary movement of the second member within the first member and for the production of an air gap between the first and second members and provided with a plurality of slots at spaced positions along the outer periphery, the slots in the second member being shaped and disposed to provide a uniform width of material between the slots anda width of material at the inner'periphery of the second member at least as great as the'width of the material between the slots, the member of slots in the second member being different from the number of slots-in the first member and the total width of the material between all of the slots in the second member being equal to the total width of the material between all of the slots in the first member, and a plurality of windings each extending through a different one of the slots in the first member and around the outer periphery of the member and having a particular number of turns for the production, in the continuous annular portions of the first and second a members and in the air gap at angularly displaced positions from the corresponding positions in the continuous annular portion of the first member, of flux dependent upon the number of turns in each winding and for the 7 production of an output voltage in accordance with the relative displacement between the first and second, memhers and in accordance with the incremental flux distribution at progressive angular positions along the air gap, the number of turns in adjacent windings being difierent in accordance with the incremental fiux distribution to be produced at progressive positions along the air gap corresponding to the annular disposition of the adjacent windings so as toobtain the'production of the desired and the number and polarity of turns in adjacent slots being chosen to produce a total flux of zero in the first and second members. 7 i

ll. In an electromagnetic transfer device, a first member made from magnetic material anddisposed in a loop and provided with a plurality of slots at spaced intervals around one periphery of the member and with teeth at spaced intervals along the second periphery of the member to define a volume between the teeth at least equal to the volume within the slots and provided with a continuous portion at its second periphery to obtain a flow of magnetic flux around the continuous portion of the first member, a second member made from magnetic material and disposed in a loop and provided with dimensions to fit within the first member for movement relative to the first member and provided with a plurality of slots different from the number of slots in the first member and at the periphery of the loop contiguous to the slots in the first member and provided with a continuous portion at its second periphery, a plurality of windings extending through the slots and the volume between the teeth and having ampere-turn characteristics limited by the volume between the slots and the volume between the teeth to produce an unsaturated flux even with a number of turns completely filling these volumes'and to produce a flux extending through the continuous portion of the first member with an intensity related at any position to the ampere-turn characteristics of the windings in the contiguous slots and extending across the air gap between the first and second members with an intensity related at any position to the intensity of the flux in the continuous portion at'a displaced position for the production of anoutput signal at any position having amplitude characteristics indicating the relative displacement between the first and second members, adjacent windings having different numbers of turns in accordance: with increments in flux to be generated at successive positions in the air gap corresponding to the relative disposition of the adand with a hollow configuration defined by an inner diameter linearly related to the particular diameter and provided with a plurality of slots at spaced positions along 'the inner periphery of the member, the outer peripheries of the slots being defined bya diameter linearly related to theparticular diameter and being defined at their radial extremities by radii of curvature dependent upon the particular diameter and being defined at their angular extremities 'by lines to define bars having substantially constant widths dependent upon the particular diameter and upon the number of slots in the'member and to define at the outer periphery a continuous annular portion having dimensions related to the widths of the bars for-the production in the member .of unsaturated flux close to ithe'saturation level, a'seeond member made from magnetic material and provided with an annular configuration having an outer diameter linearly related tol the particular diameter for disposition within the first member for rotary movement and providedwith a hollow configuration defined byv an inner diameter linearly related to the particular diameter and provided with a plurality of slots at spaced positions along the inner periphery output voltage upon the occurrence of progressive angular displacements between the first and second members of the member, the inner peripheries of the slots being i ,define'bars having substantially constant widths depend entupon the particular diameter and upon the number of slots in the member and having for all of the bars a combined Width equal to the combined Width of the bars in the first member and to define at the inner periphery a continuous annuiar portion having dimensions corresponding to the width of the continuous annular portion in the first member for the production in the member of unsaturated flux having levels corresponding to the levels of the flux in the first member, and a first plurality of windings extending through the slots in the first member and a second plurality of windings extending through the slots in the second member to obtain the production of output signals in pattern dependent upon the pattern of disposition of the windings in the slots for progressive displacements between the first and second members, the number of turns in adjacent windings in at least a particular one of the members being ditferent in accordance with the production of desired flux increments at successive annular positions to obtain the production of the desired output signals for progressive displacements between the first and second members and the polarity and number of turns in the adjacent windings in the particular member being chosen to produce a total flux of zero in the members.

13. In an electromagnetic transfer device, a first member made from magnetic material and provided with an annular configuration and with a plurality of teeth at spaced positions along the outer periphery and with a particular diameter to the tips of the outer teeth and with a first particular fraction of the particular diameter to the inner position of the teeth and provided with a plurality of slots at spaced positions along the inner periphery of the member, the outer peripheries of the slots being defined by a second particular fraction of the particular diameter and at their extremities by curvatures dependent upon the particular diameter to define bars having substantially constant widths between the teeth and a continuous annular portion between the slots and the beginnings of the teeth for the production of unsaturated flux close to the saturation levels of the material and to define substantially equal volumes within the slots and between the continuous-portion of the first member and the tips of the teeth, a second member made from magnetic material and provided with an annular configuration and disposed within the first member in concentric relationship to the first member for rotary movement relative to the first member and provided with an outer diameter defined by a third particular fraction of the particular diameter and provided with a plurality of slots at spaced positions along the outer periphery of the member, the slots in the second member being defined at their inner peripheries by a fourth particular fraction of the particular diameter and at their extremities by curvatures dependent upon the particular diameter to define bars having substantially constant widths between the teeth and having for all of the bars a total width equal to the total width of all of the bars in the first member and to define between the slots and the inner periphery of the member a contiuous annular portion having a width equal to the width of the continuous annular portion in the first member for the production of unsaturated flux close to the saturation levels of the material, and a first plurality of windings disposed in the slots in the first member and a second plurality of windings disposed in the slots in the second member to obtain the production of a signal having particular characteristics upon progressive displacements between the first member and the second member and in accordance with the distribution of the windings in the different slots, the windings in the adjacent slots in the first member having different numbers of turns in accordance with the incremental pattern of the flux to be produced at successive positions across the air gap corresponding to the annular positioning of the adjacent slots and the windings in adjacent slots being wound with a polarity and being provided with a number of turns to obtain a sum of zero for all of the turns on the first member upon a consideration of a positive value for one polarity in the turns and a negative value for the other polarity in the turns.

14. In an electromagnetic device as set forth in claim 12, the windings on the first member being wound toroidally to provide for an extension of each winding through only one of the slots for the production of a particular pattern of signals upon progressive displacements between the first and second members and in accordance with the number of turns in each winding.

15. in an electromagnetic device as set forth in claim 13, each of the windings on the first member being wound toroidally to extend through a different one of the slots in the first member and around the outer periphery of the first member and each successive winding having a number of turns and direction of current flow therein dependent upon the pattern of the signals to be generated upon progressive angular displacements between the first and second members.

References Cited in the file of this patent UNITED STATES PATENTS 226,483 Braunsdorf Apr. 13, 1880 228,544 Maxim June 8, 1880 501,117 Tyler July 11,1893 1,488,876 Hambright Apr. 1, 1924 1,566,939 Welch Dec. 22, 1925 1,955,111 Buckler Apr. 17, 1934 2,248,616 Fans July 8, 1941 2,590,845 Curry Apr. 1, 1952 

